Raspberry Pi becomes vehicle ECU

The Twike, manufactured by Fine Mobile in Germany, is half-bike and half-electric car for one or two people: it has a 3kW motor (8kW peak), pedals, a lightweight frame, and weather-proof body.  Maximum speed is 53mp.

For his masters project at École Polytechnique Fédérale de Lausanne (EPFL) in Switzerland, Hoffet set about improving the existing model.

For an on-board computer, he integrated a Raspberry Pi – connected to the on-board serial bus – to collect and display useful information for the driver. Various parameters – such as speed, pedalling power and battery life – now appear on a screen. It also stores data for later analysis.

“This system was implemented on the current version of the vehicle – Twike 3 – but it’s actually designed to exploit even more data on the new Twike that should come out in the next year or two,” said EPFL.

The drive-train has gears and chain similar to that of a bicycle. “Since Twikes have only five speeds, you end up having to pedal too fast at higher speeds,” said Hoffet.

In response, he eased pedalling effort by using the Raspberry Pi to mediate between motor, 353V Ll-ion battery and pedalling speed, said EPFL, which added: “Some final adjustments still need to be made to the system before it’s completely finalised.”

Twikes were invented in Switzerland in the 1990s.

“I first realised how handy Twikes can be when I was at EPFL and saw a researcher come to campus in one,” said Hoffet.

When his internship at another company fell through, he applied to work at Fine, where it so happened the company was developing a new model, and ended up there for six months on his project.

In his spare time, Hoffet renovated a Twike and returned to Switzerland in it.